Squaring & Diagonal Calculator
Check rectangular layouts using the expected corner-to-corner diagonal or generate a scaled 3-4-5 triangle.
Results
Side A
—
Side B
—
Diagonal
—
Use the result as a planning estimate and verify project-specific dimensions and product information before ordering or cutting.
How it works
For a rectangle, the diagonal comes from the Pythagorean theorem. The 3-4-5 mode scales a right triangle while preserving its right angle.
diagonal = √(side A² + side B²)Worked example
A 10 ft × 8 ft rectangle has a diagonal of about 12 ft 9 11/16 in.
Assumptions
- Sides meet at a right angle when the measured diagonal matches the calculated value.
Limitations
- Field measurements and layout tolerances determine how closely the diagonals need to match.